Telephone exchange system



June 14, 1932. HOVLAND 1,863,307

TELEPHONE EXCHANGE SYSTEM Filed Jan. 27. 1931 2 Sheets-Sheet l NYE/V70}?y H. HOI LAND A 7' TOENE) June 14, 1932. H. HOVLAND TELEPHONE EXCHANGESYSTEM Filed Jan. 27, 1931 2 Sheets-Sheet lNVENTOR H. HOVLAND 01 161 5'WW ATTORNEY Pnml-m Patented June 14, 1932 UNITED STATES PATENT OFFICE IHENRY HOVLAND, OF WILLISTON PARK, NEW YORK, ASSIGNOR TO BELL TELEPHONELABORATORIES, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION OF NEWYORK TELEPHONE EXCHANGE SYSTEM Application filed January 27, 1931-. semiNo. 511,511.

15 calling line to identify the calling station and to operate thecorresponding servicemeter if the call is answered. If the calledstation is on the same line as the calling station, the connection isextended to a rover! ing-call selector circuit which is arranged toautomatically ring the called station as soon as the calling subscriberreplaces the receiver upon the switchhoolz. On such a call the op-,cration of the service-meter is controlled by an operator whosupervises the, call in order that no chargewill be made if the callingsubscriber again removes the receiver to release the connection prior tothe answer oi the called subscriber. Such a system is disclosed inPatent 1,695,828 issued December 18, 1928' to R'. L. Stokely.

According'to the present invention the re verting-call selector circuitis also arranged to receive an indication from the charging trunk as towhich station is the calling station, to test the calling line as soonas the ringing is stopped by the removal of thereceive'r at one of thestations, and to initiate the operation of the calling subscribensservice-meter by reversing. the current over the conductors of thecharging trunk only in case the answering station is the called station.

The invention will be better understood by considering'atelephone'sy'stem in which Referring to the drawings,

Fig. 1 shows a subscribers line 1 serving the stations A and B, a linefinder LF, and a trunk circuit T arranged to determine which of thestations is the calling statioir and to control the operation of thecorresponding message register.

Fig. 2 shows a first selector switch S which is 'aeri'naii'entlyassociated with the line finder LF and trunk T of Fig. 1, and arevertingcall' selector RS which is used on calls between subscribers onthe same line.

The invention is not limited in its use to the system illustrated in thedrawings but may be applied in any automatic telephone system havingmessage-rate party-line subscribers.

The subscribers stations A and B, the line finder LF, the trunk circuitT, and the first selector switch S are similar to those shown 7 anddescribed in my Patent No. 1,823,688 dated Sept. 15, 1931, except thatthe trunk circuit has been modified by adding resistance 90 and byadding the outer left-hand contacts of relay 33; when thus modified thetrunk circuit is able to indicate the identity of the calling station tothe reverting-call selector which is used when one of the stations on aparty line calls another station on the same line. The operation of theline finder, trunk,

It will now be assumed that a call is made 3' from one of the stationsof line 1 to the other station onthe same line. The line 1 is thereuponextended through the brushes of line finder LF and trunk T to the firstselector S. The calling subscriber then dials the code The revertingwallsenumber of the called station assigned for use on reverting calls, theimpulses thus created being received by the line relay 30 of trunk T andrepeated over conductors 56 and 5'7. The selector switch S isselectively operated in response to impulses corresponding to the firstdigit dialed to select a group of trunks all of which connect toreverting-call selectors. The selector S then automatically hunts forand seizes an idle trunk in this group, which we will assume to beconnected to the selector RS. Immediately after receipt of the firsttrain of impulses, the test relay 31 of trunk T is connected to bothsides of the calling line to determine which of the stations is thecalling station. If the call originated at station A, relay 31 operatesthereby causing the operation of relay 33; if the call originated atstation B, both of relays 31 and 33 remain normal. If relay 33 operates,it looks under the control of relays 34 and 37 The operations so farmentioned are described in detail in my aforementioned patent.

When the selector S extends the connection from line 1 through itsbrushes to the reverting selector RS, a circuit is closed for operatingthe line relay 101; this circuit is traced from battery through thewinding of relay 101, the outer lower back contacts of relays 104 and110, conductor 92, through brush 7 2 and conductor 57 of the selector S,right-hand winding of relay 55 in thetrunk circuit T, outer lower backcontact of relay 40, lower back contact of relay 32, retard coil 46,upper contact of relay 30, the outer upper back contact of relay 41, theleft-hand winding of relay 55, conductor 56 and brush 71 of selector S,conductor 91, through the outer upper back contacts of relays 110 and104, and though the winding of retard coil 108 to ground. Re-

lay 101 closes an obvious circuit for operating relay 102. Relay 102connects ground through its middle upper front contact over conductor93, through brush 73 of selectors to conductor 59 to prevent the releaseof the selector S and line finder LF. Relay 102 also connectsgroundthrough its outer upper front contact and the inner upper backcontacts of relays 110 and 104 to the alarm circuit 128; if neither ofrelays 104 and 110 operates with in a predetermined length of time afterrelay 102 has operated, the alarm circuit functions to signal amaintenance man in the usual manner.

At the same time that the circuit for operating the line relay 101 isclosed, another circuit may be traced from ground through the right-handwinding of marginal relay 112, over conductor 94, brush 74 and conductor58 of selector S through theright-hand back contact of relay 34 in trunkT, conductor 49, through the winding of relay 40 to battery.

1]: the call originated at station A, relay 33 is operated; in whichcase the connection 3' from the winding of relay 112 of thereverting-call selector RS is also extended from conductor 49 of trunk Tthrough the outer left-hand front contact of relay 33 and resistance 90,to battery thereby causing the operation of relay 112 as well as relay40. But, if the call originated at station B, relay 33 is normal so thatthe resistance 90 is not connected in parallel. with the winding ofrelay 40; and in this case relay 40 operates but relay 112 does notoperate. If operated, relay 112 locks through its lefthand winding andfront contact over conductor 115 to ground at the inner upper frontcontact of relay 102 the lefthand contacts of relay 112 close before theright-hand winding is shunted by the inner right-hand front contact.

The next set of impulses, received by the line relay 30 of trunk T, isrepeated over conductors 56 and 57 through brushes 71 and 72 of selectorS, to the selector RS thereby causing relay 101 to be alternatelyreleased and recperated in response to each impulse. Relay 102 is aslow-to-release relay and remains operated during the receipt of thistrain of impulses. The release of relay 101 in response to thefirst'impulse closesa circuit for operating relay 103 and rotary magnet111; this circuit may be traced from ground through the back contact ofrelay 101,'the lower front contact of relay 102, the left outer backcontact of relay 106, conductor 114, through the normally closed contactof the od-normal springs ON, conductor 113, through'the winding of relay103 to battery; 0 and from conductor 113through the next-tothe-outerlower armature and back contact of relay 110 through the winding ofrotary magnet 111 to battery. The operation of magnet 111 advances thebrushes 116, 117, 118 and 119 into contact with the first set ofterminals in the associated bank. As soon as the switch is moved out ofits normal posiion, the oil-normal springs ON are operated so that theoperating circuit through the windings of relay 103 and magnet 111 isnow traced from conductor 114 to conductor 113 through the inner lowerfront contact of relay 103 instead of through the lower contact of theON springs. When relay 101 reoperates at the end of the first impulse,magnet 111 releases; but relay 103 is a slow-to-release relay and itremains operated until all of the impulses in the train have beenreceived. Each release and reoperation of relay 101 in response toimpulses is thus effective to cause the operation and release of magnet111, thereby advancing the brushes of switch RS to a corresponding ofterminals. The terminals in the banks of the reverting-call selectorsare connected as shown in the aforementioned patent to R. L.Stolrely,this arrangement being adapted for use with lines having notmore than four parties.-

No further operation takes place until the calling subscriber replacesthe receiver upon T :through the winding of relay 110, brush 118,conductor 120, brush 119, the upper back contact of relay 103, themiddle left-hand back contact of relay 106, and through the lower frontcontact of relay 102 to ground at the back contact of relay 101. henrelay 110 operates, relay 103 is reoperated in a circuit which may betraced from battery through its winding, conductor 113, the outer lowerfront contact of relay 110, conductor 11 1, the

left outer back contact of relay 106, the

lower front contact of relay 102, to ground at the back contact of relay101. Relay 102 does not rel-ease when the calling subscriber hangs upsince this relay is held operated in a circuit through the inner upperfront contact of relay 110. Relay 110 also closes a circuit for startingthe ringing interrupter 123, by connecting conductor 124 to conductor125. Relays 105 and 107 of the revertingcall selector RS are nowoperated in response to impulses transmitted over conductors 121 and 122from the interrupter circuit 123, so as to ring both the calling andcalled stations. The circuit for operating relay 105 may be traced frombattery through its winding, a front contact of relay 110, through brush116, over conductor 122 to the ringing interrupter 123. The circuit foroperating relay 107 is traced from battery through its winding, a frontcontact of relay 110, brush 117, over conductor 121 to the ringinginterrupter 123. lVith relay 107 operated and relay 105 normal, theringing circuit is closed from the ringing source 130, through the frontcontact of relay 107, the left-hand winding of relay 106, the left-handback contact of relay 105, the right-hand back contact of relay 106,over conductor 92,'through brush 72 and conductor 57 of selector S,through the righthand winding of relay 55 of trunk circuit T, the lowerfront contact of relay 40, the middle lower armature and back contact ofrelay 39, over conductor 27, through brush 12 of line finder LF, andover the ring conductor of line 1 to operate the ringer at station E.Vith relay 107 operated and relay 105 also operated, the ringing circuitis traced from the source of ringing current 130, through the frontcontact of relay 107, the left-hand winding of relay 106, the right-handfront contact of relay 105, the inner left-hand back contact of relay106, the outer upper front contact of relay 110, over conductor 91,through brush 71 and. conductor 56 of selector S, through the left-handwinding of relay 55 of trunk circuit T, the upper front contact of relay40, the upper back contact of relay 39, over conductor 26, through brush11 of line finder LF, over the tip conductor of line 1 to operate theringer at station A.

The subscribers at stations A and B are thus alternately signaled underthe control of the ringing interrupter 123 until the receiver is removedat the one or the other of these stations, at which time the currentthrough the left-hand winding of relay 106 is increased sufficiently tocause the operation of this relay. Relay 106 looks through itsright-hand winding and inner right-hand front contact, over conductor115 to ground at relay 102. Relay 106 opens the ringing circuit andopens the locking circuit of relay 103 and closes a connection frombattery through the winding of relay 109, the inner left-hand frontcontact of relay 106, the outer upper front contact of relay 110,conductor 91, through brush 71 and conductor 56 of selector S, throughthe left-hand winding of relay 55 of trunk circuit T, the upper frontcontact of relay 10, the upper back contact of relay 39, over conductor26, through brush 11 of line finder LF, to the tip conductor of line 1';relay 106 also closes a connection from battery through the winding ofrelay 109, the. inner lower front contact of relay 110, the outerright-hand front contact of relay 106, conductor 92, through brush 72and conductor 57 of selector S, through the righthand winding of relay55 of trunk circuit T, the lower front contact of relay 40, the innerlower back contact of relay 39, through brush 12 of line finder LF, tothe ring conductor of line 1. If the receiver has been removed atstation A, relay 109 is operated by the identifying ground at 10; but ifthe receiver is removed at station E, relay 109 does not operate. Sincerelay 110 is looked under the control of relays 103 and 102 and sincerelay 103 is a slow-to-release relay, this circuit to ground at 10 isclosed long enough for relay 109 to operate. WVhen relay 103 releases, acircuit is closed for operating relay 104 if the call has been answeredby the called station but is not closed if the call was answered by thecalling station. If the call originated at station A and ringing isstopped by the answer of station E, relay 109 is normal and the circuitfor operating relay 104 may be traced from battery through its winding,the lower back contact of relay 103, the outer right-hand front contactof relay 112, the back contact of relay 109, and through the innerright-hand front contact of relay 106, over conductor to ground at relay102. If the call originated at station 13 and ringing is stopped by theanswer of station A, relay 109 is operated and the circuit for operatingrelay 104 may be traced through the back contact of relay 112 and thefront contact of relay 109 instead of through the front contact of relay112 and the back contact of relay 109. In case the receiver is removedby the calling subscriber to stop the ringing before the call isanswered at the called station,

relay 104 is not operated and the secondary l winding of transformer 127-is connected through the inner lower back contacts of relays 104 and110, and throughthe outer right-hand front contact of relaylOG toconductor 92 so as to transmit a tone to the subscribe-rs line and thusprevent conversation between the calling and called stations in case thecalled subscriber answers the call after the ringing has been stopped bythe calling subscriber.

The aforementioned operation of relay 106 is also effective to cause therelease of relay 110; and with relay 1-10 released, relay 101 reoperatesand remains operated until the receivers are replaced at both thecalling and called stations. WVith relay 110 released relay 102 is heldoperated under the control of line relay 101. With relay 10.4 operated,the connections between conductors 91 and 92 and the windings of linerelay 101 and retard coil 108 are reversed so that the current throughthe windings of the polarized supervisory relay 55 in the trunk circuitT is eiiective to cause the operation of relay 55; and the messageregister of the calling station is operated as described in myaforementioned patent.

Although the reverting-call selector BS is arranged for tw0-partyservice, it is suitable for use. with four-party lines asv far asringing is concerned and can easily be modified, by anyone skilled inthe art, so as to be capable of determining which of the stations on afour-party line is the answering station. A trunk circuit arranged fordetermining which of the stations on a four-party line is the callingstation is disclosed in the patent to It. L. Stokely, No. 1,799,654dated April 7, 1931; and the station identifying means provided in aiourparty reverting-call selector might be similar to that provided inthis trunk circuit. 7

What is claimed is: I

1. In a telephone system, a line having a plurality of subscribersstations permanently connected thereto, a reverting-call selector foruse when the subscriber at one of said stations calls another of saidstations, means including a trunk for extending said line to saidselector, means associated with said trunk for testing said line todetermine which of said stations is the calling station, means forindicating the'result of said test to said selector, and meansassociated with said selector for determining the station at which. thecall is answered. I T

2. In a telephone system, a line, a plurality of subscribers stations onsaid line, a reverting-call selector for use when the subscriber of saidcall by the called station for operating said supervisory relay.

3.- In a telephone system, a line, a plurality of subscribers stationson said line, a reverting-call selector for use when the subscriber atone of said stations calls another of said stations, means including atrunk for extending said line to said selector, a supervisory relayassociated with said trunk, means associated with said trunk for,testing said line to determine which of said stations is the callingstation, means for indicating the result of said test to said selector,means associated with said selector for determining the station at whichthe receiver is removed to answer the call, and means efiective in consequence of the answer of said call by the called station butineffective in consequence of the removal of the receiver at the callingstation for operating said supervisory relay.

1. In a telephone system, lines, subscribers stations, a plurality ofsaid stations being permanently connected to one of said lines,service-meters one for each of said stations, at reverting-call selectorfor use when the subscriber at one of the stations on said one of saidlines calls another of the stations on said line, means including atrunk for extending said line to said selector, a supervisory relay insaid trunk for initiating the operation of the calling stationsservicemeter in consequence of the answer of the called station, meansassociated with said trunk for testing said line to determine which ofsaid stations is the calling station, means for indicating the result ofsaid test to said selector, means associated with said selector fordetermining the station at which the receiver is removed to answer thecall, and means effective in consequence of the answer of said call bythe called station for operating'said supervisory relay.

5. In a telephone system, a line, a plurality of subscribers stations onsaid line, a reverting-call selector for use when the subscriber at oneof said stations calls another of said stations, means including a trunkfor extending said line to said selector, a servicemeter for each ofsaid stations, means associated with said trunk for testing said line todetermine which of the stations is the calling station, means forindicating the result of said test to said selector, a supewisory relay,means rendered effective by the operation of said relay and associatedwith said trunk for operating the calling stations servicemeter, meansassociated with said selector and rendered effective by replacing thereceiver at the calling station for ringing over said line, means forstopping the ringing upon the removal of the receiver at any of saidstations, means associated with said selector for testing the line todetermine the station at which the receiver is removed, and means foroperating said relay if the station at which the receiver is removed isthe called station.

6. In a telephone system, lines, subscribers stations, a plurality ofsaid stations being permanently connected to one of said lines,service-meters one for each of said stations, means including a trunkfor extending said line upon the origination of a call at one of saidstations, means associated with said trunk for determining which of saidstations is the calling station, a supervisory rela in said trunk forinitiating the operation 0 the calling stations register in consequenceof the answer of the called station, a revertingcall selector for use oncalls from one to another of the stations on said one of said lines,means associated with said selector for transmitting ringing currentover said line, means for stopping the ringing in consequence of theremoval of the receiver at one of the stations on said one of saidlines, means associated with said selector for determining whether thestation at which the receiver is removed is the same station as wasfound by said trunk to be the calling station, and means for opergQating said supervisory relay only in case the station at which thereceiver is removed is the called station.

7. In a telephone system, party lines each I having a plurality ofsubscribers stations connected thereto, a service-meter individual toeach of the stations on said lines, metering equipment for associationwith said lines, revertive-call equipment, means responsive to theorigination of a call from one to another of the stations on one of saidlines, for associating said metering and revertive-call equipment withthe line of said calling station, means individual to said meteringequipment for determining which of said stations on said calling line isthe calling station, means for recording the result of saiddetermination in said revertive-call equipment, means effective inresponse to replacing the receiver at the calling station for ringingthe called and the calling stations, means actuated in consequence ofthe removal of the receiver at either of the called or calling stationsfor stopping the ringing, means individual to said revertive-callequipment for determining the station at which the receiver is removed,and means effective to initiate the operation of the calling stationsservice-meter if it is found that the receiver was removed at the calledstation but ineffective to initiate the operation of said meter if it isfound that the receiver was removed at the calling station.

In witness whereof,'I hereunto subscribe my name this 22 day of January,1931.

HENRY HOVLAND.

